From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4CE3C433E0 for ; Mon, 8 Feb 2021 01:14:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 920E064E24 for ; Mon, 8 Feb 2021 01:14:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229623AbhBHBOL (ORCPT ); Sun, 7 Feb 2021 20:14:11 -0500 Received: from mail.loongson.cn ([114.242.206.163]:37494 "EHLO loongson.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229537AbhBHBOK (ORCPT ); Sun, 7 Feb 2021 20:14:10 -0500 Received: from [10.130.0.55] (unknown [113.200.148.30]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9AxOdUpkCBgpgUIAA--.10238S3; Mon, 08 Feb 2021 09:13:14 +0800 (CST) Subject: Re: [PATCH v2 2/4] MIPS: microMIPS: Fix the judgment of mm_jr16_op and mm_jalr_op To: "Maciej W. Rozycki" , Thomas Bogendoerfer References: <1611207098-11381-1-git-send-email-hejinyang@loongson.cn> <1611207098-11381-3-git-send-email-hejinyang@loongson.cn> Cc: Jiaxun Yang , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Burton , Jun-Ru Chang From: Jinyang He Message-ID: <32bd50ed-c359-0efc-af76-4b77a3fc05ae@loongson.cn> Date: Mon, 8 Feb 2021 09:13:13 +0800 User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-CM-TRANSID: AQAAf9AxOdUpkCBgpgUIAA--.10238S3 X-Coremail-Antispam: 1UD129KBjvJXoWxJrWUCF15AFWrJr4Dur1rWFg_yoW8Kr13pF WYva9FyF4kJFyrA34kJayrX345Aan5Kay3GF15t345twn8Wr1avFyftw4S9wn7Gr4Yk3WI qFy3XrWUuwnavaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvSb7Iv0xC_Kw4lb4IE77IF4wAFF20E14v26r4j6ryUM7CY07I2 0VC2zVCF04k26cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rw A2F7IY1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xII jxv20xvEc7CjxVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_Gr1j6F4UJwA2z4x0Y4 vEx4A2jsIEc7CjxVAFwI0_Gr1j6F4UJwAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40E FcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr 0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI48JMxk0xIA0c2IEe2xFo4CEbIxv r21lc2xSY4AK67AK6w4l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2 IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v2 6r126r1DMIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2 IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWrZr1j6s0DMIIF0xvEx4A2 jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUvcSsGvfC2KfnxnUUI43 ZEXa7IU5s6pJUUUUU== X-CM-SenderInfo: pkhmx0p1dqwqxorr0wxvrqhubq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/08/2021 05:31 AM, Maciej W. Rozycki wrote: > On Thu, 21 Jan 2021, Jinyang He wrote: > >> mm16_r5_format.rt is 5 bits, so directly judge the value if equal or not. >> mm_jalr_op requires 7th to 16th bits. These 10 which bits generated by > The minor opcode extension field is comprised of bits 15:6, not 16:7 as > your description suggests. Please be accurate with statements. > >> shifting u_format.uimmediate by 6 may be affected by sign extension. > Why? The `uimmediate' bit-field member is unsigned for a reason. No > sign-extension is made on unsigned data with the right-shift operation. > >> Thus, take out the 10 bits for comparison. >> >> Without this patch, errors may occur, such as these bits are all ones. > How did you come to this conclusion? > >> diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c >> index d737234..74d7fd8 100644 >> --- a/arch/mips/kernel/process.c >> +++ b/arch/mips/kernel/process.c >> @@ -292,8 +292,8 @@ static inline int is_jump_ins(union mips_instruction *ip) >> * microMIPS is kind of more fun... >> */ >> if (mm_insn_16bit(ip->word >> 16)) { >> - if ((ip->mm16_r5_format.opcode == mm_pool16c_op && >> - (ip->mm16_r5_format.rt & mm_jr16_op) == mm_jr16_op)) >> + if (ip->mm16_r5_format.opcode == mm_pool16c_op && >> + ip->mm16_r5_format.rt == mm_jr16_op) >> return 1; >> return 0; >> } > Code style changes should be submitted on their own as separate patches. > >> @@ -305,7 +305,7 @@ static inline int is_jump_ins(union mips_instruction *ip) >> if (ip->r_format.opcode != mm_pool32a_op || >> ip->r_format.func != mm_pool32axf_op) >> return 0; >> - return ((ip->u_format.uimmediate >> 6) & mm_jalr_op) == mm_jalr_op; >> + return ((ip->u_format.uimmediate >> 6) & GENMASK(9, 0)) == mm_jalr_op; > You've now excluded JALR.HB, JALRS, and JALRS.HB instructions. The mask > was there for a reason. If you can't be bothered to verify microMIPS > changes say with QEMU, then at the very least please check documentation. > The intent of this code is clear and these instructions are even spelled > out explicitly in the comment at the top. It's my fault. :-( How amazing the opcode design is! Thanks, Jinyang > Thomas, please revert this change as I can see you've already taken it. > It's plain wrong. > > Maciej